I've been waiting for this to be implemented in the extension, using any kind of storage(I figured bookmarks would have made more sense. Sidewise is basically a really good bookmark manager that integrates with tabbed browsing really well, and they are already synced by Chrome). A google sheet works pretty well too, just a setting to automatically import on startup and export on shutdown would basically automate the whole thing. Thanks for making this, I'll be sure to send over an email, hopefully the developer implements something like this soon.